Microsoft co-founder Bill Gates, pictured in a July 28, 2011, file photo, is among a number of wealthy Americans on Forbes' annual list with ties to San Diego.
/ AP

You might see them placing bets at the Del Mar Racetrack, taking in a Broadway show at the La Jolla Playhouse or landing a yacht at the Kona Kai Marina.

They are the richest of the rich, and they live here, too. At least 20 people on Forbes’ annual list of the 400 wealthiest Americans have ties to San Diego County, according to U-T reporting and a review of newspaper archives and property records.

That includes Microsoft co-founder Bill Gates, whose $59 billion net worth ranks him ahead of all the other billionaires who make up this year’s list. He’s a member of the exclusive Del Mar Country Club, owned by the wife of another person who made the list: T. Boone Pickens.

Some of those listed on what Forbes calls “the ultimate scorecard” are self-made entrepreneurs, while others are heirs to fortune.

The list includes the owners of San Diego institutions such as Qualcomm, the San Diego Chargers and The San Diego Union-Tribune. There are members of the Hyatt Hotels and Walmart families here, too.

For the most part, these residents shy away from publicity. They spend time in the enclaves of Rancho Santa Fe and La Jolla as well as working-class National City and Del Mar, home to the renowned summer race meet. They do come out for charity functions, with many of them known for their philanthropy.

We pulled together information on some of the county’s wealthiest residents. Here’s who made the Forbes’ list:

Microsoft co-founder Bill Gates, $59 billion. Gates, 55, has a home in the Del Mar Country Club in Rancho Santa Fe, although he lists his primary residence as Medina, Wash.

The world’s richest woman, Walmart family member Christy Walton, $24.5 billion. Walton, 56, lives in Jackson, Wyo., and used to own a house in National City that she donated to a charity in 2006; she has been spotted in recent years at La Jolla and Balboa Park events.

Construction/mining entrepreneur Dennis Washington, $5 billion. Washington, 77, lives in Missoula, Mont., and often visits San Diego; his yacht is sometimes moored here and he has been spotted at the Del Mar Racetrack.